This disclosure relates to an apparatus for manipulation of an implantable medical device and exemplary methods of using the apparatus to manipulate the implantable medical device in conjunction with a surgical procedure. For example, this disclosure describes exemplary embodiments for electrically-controlled rotational manipulation of a pacing lead to wind a helical tip of the pacing lead into an implant location until the pacing lead is seated. However, it will be appreciated that the disclosed concepts may have usefulness in manipulation of other implantable medical devices, such as other types of leads and therapy delivery tubes. Moreover, manipulation of the implantable medical device can also include unwinding the helical tip from the implant location as well as actuator-controlled grasping and releasing of the implantable medical device.
By way of background, electrical stimulation of body tissue and organs as a method of treating various pathological conditions is becoming quite commonplace. Such stimulation generally entails making some type of electrical contact with the body tissue or organ. In particular, with respect to the heart, electrical leads have been implanted by a thoracotomy in which an electrode formed on the end of the lead is physically implanted into the myocardial tissues.
Various electrode structures and various techniques for implanting electrode structures into such body tissue as the heart or myocardium, have been developed. Typically, electrodes attached to the heart are stimulated by a cardiac pacemaker which may be implanted within the patient's body.
Many medical electrode placement systems have been devised to assist in attaining accurate placement. Many of them utilize the principle of grasping an insulating head from which the electrode projects with an introducer, positioning the electrode appropriately, then releasing the head and withdrawing the tool.
A typical cardiac stimulating lead comprises an elongated lead body having a proximal and distal end. The lead body includes one or more flexible electrical conductors contained within a pliable, flexible insulating sheath. Suitable connectors are affixed to the proximal end of the conductors for facilitating attachment to an implantable or external electrical stimulating pulse generator. Affixed to the distal end of the lead body are one or more electrodes which are joined to the embedded conductor(s).
One known type of stimulating lead is the so-called myocardial screw-in lead. In this arrangement, one of the electrodes comprises a rigid helix having spaced-apart convolutions. It is supported by a molded plastic head, with the helix projecting perpendicularly from a surface of the head. The lead is installed using a specially designed tool which frictionally grasps the lead head, allowing the helix to be rotated into and anchored by the tissue to be stimulated. Thus, the tool is used much like a screw driver.
In the medical field, implantable leads are used with a wide variety of medical devices. For example, implantable leads are commonly used to form part of implantable cardiac pacemakers that provide therapeutic stimulation to the heart by sensing electrical activity of the heart and delivering pacing, cardioversion or defibrillation pulses via electrodes disposed on the leads, e.g., typically near distal ends of the leads. Leads may also be used to deliver therapeutic agents. A number of challenges exist with respect to medical leads; in particular, as more advanced and complex therapeutic techniques are developed, new configurations are required to facilitate fixation of lead electrodes at alternate implant sites within a patient.
It is desirable for a lead to be implanted with the center axis of the helical electrode normal to the surface of the heart. The existing rigid introducers often require a straight line between the point of entering the body and the implant position on the heart. This alignment is extremely challenging since the target spot is not directly visualized. Many or most traditional lead introducers are not suited for a minimally invasive (MI) approach due to their size and need for a straight-line approach. When leads must be placed on the superior portion of the left ventricle, as with resynchronization therapy, specialized tools and methods must be employed to reduce trauma to the patient and reach the appropriate location.
Based on the foregoing, a solution that simplifies manipulation of implantable medical devices, particularly rotational manipulation, is desirable. Additionally, a solution that that overcomes at least a portion of the drawbacks associated with current techniques for rotational manipulation of implantable medical devices is desirable.